Acid assisted cold welding and intermetallic formation and dental applications thereof

Abstract

A metallic composite solid, containing alloys and/or intermetallics, is formed by compacting at moderate pressure a mixture of powder particles, foils or sheets at a temperature close to room temperature, well below the melting temperature of the constituent components and without the addition of low melting metals such as mercury, indium or gallium acting as a sintering agent. This low temperature consolidation of the powder mixture is enhanced by having the surface oxide of the powder particles removed, prior to consolidation, and/or by coating the particles with an oxide-replacing metal such as silver or gold. The coating process may be replacement reactions, autocatalytic reduction or electrolytic reduction. The composite formation is assisted by the addition of a liquid acid such as fluoroboric acid, sulfuric acid, fluoric acid, adipic acid, ascorbic acid, or nitric acid. A preferred embodiment of the process for metal solid composite formation is a process for forming dental restorative materials at ambient temperatures and under pressure exerted by manual dental instrumentation.

What is claimed is:  
     
       1. A process for forming dental restorative materials at ambient temperature and under pressure exerted by dental manual intrumentation comprising: 
       surface treating a hard intermetallic or metallic component by coating it with a noble metal,  
       adding the surface treated hard intermetallic or metallic component to a dilute acid to form a slurry, and  
       consolidating the slurry into a solid mass using manual dental intrumentation.  
     
     
       2. The process according to  claim 1 , wherein the hard intermetallic is Ag 4 Sn. 
     
     
       3. The process according to  claim 1 , wherein the metal is tin and the noble metal is Ag. 
     
     
       4. The process according to  claim 2 , wherein the noble metal is Au, Ag, Pt, or Pd. 
     
     
       5. The process according to  claim 1 , wherein the noble metal is present in a volume which is from about 10 to about 100% of a mixture of the hard intermetallic or metallic component and the noble metal. 
     
     
       6. The process according to  claim 1 , wherein the consolidation is performed in situ in the oral cavity of a dental patient. 
     
     
       7. The process according to  claim 1 , wherein the acid is selected from the group consisting of acetic acid, sulfuric acid, fluoroboric acid, hydrofluoric acid, citric acid, adipic acid, ascorbic acid and nitric acid. 
     
     
       8. The process according to  claim 7 , wherein the acid is fluoroboric acid. 
     
     
       9. The process according to  claim 7 , wherein the acid has a concentration of from about 1% to about 30%. 
     
     
       10. The process according to  claim 8 , wherein the fluoroboric acid is in a concentration from about 2 to about 10% by volume. 
     
     
       11. The process according to  claim 10 , wherein the fluoroboric acid is in a concentration of about 2.5% by volume.